Putative paired small multidrug resistance family proteins PsmrAB, the homolog of YvdSR, actually function as a novel two-component Na+/H+ antiporter
Putative paired small multidrug resistance family proteins PsmrAB, the homolog of YvdSR, actually function as a novel two-component Na+/H+ antiporter
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假定的配对小多药耐药家族蛋白 PsmrAB（YvdSR 的同源物）实际上充当新型双组分 Na /H 反向转运蛋白
DOI：
10.1111/1574-6968.12008
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发表时间：
2013-01-01
影响因子：
2.1
通讯作者：
Yang, Lifu
中科院分区：
文献类型：
--
作者：
Jiang, Juquan;Wang, Lei;Yang, Lifu
本研究以缺乏三种主要Na+/H+逆向转运蛋白的大肠杆菌KNabc为出发菌株，从大坂盐湖嗜盐菌的宏基因组DNA中筛选Na+/H+逆向转运蛋白基因，并克隆了两个与YvdSR同源的多药耐药（PSMR）家族蛋白基因psmrAB。只有同时存在psmrAB基因，而不是单一基因，才能赋予E. coliKNabc在0.6MNaCl和碱性pH条件下的Na ~+（Li ~+）/H ~+逆向转运活性，表明该膜具有pH依赖的Na ~+/H ~+逆向转运活性。psmrAB在pH9.0时活性最高。然而，对抗菌药物的详细测试表明，E。大肠杆菌DH 5a仅对氯霉素产生轻微的耐药性，对其他代表性抗菌药物尤其是溴化乙锭均未产生耐药性。蛋白质序列比对表明，PsmrA和PsmrB与已知的单基因或多基因Na+/H+反向转运蛋白以及TetA（L）和MdfA等具有Na+/H+反向转运活性的蛋白质均不具有同源性。综上所述，PsmrAB应主要作为一种新型的双组分Na+/H+逆向转运蛋白。这是第一个表现出Na+/H+反向转运蛋白活性的PSMR家族成员的例子。
In this study, metagenomic DNA was screened for the Na+/H+ antiporter gene from the halophilic bacteria from Daban Salt Lake using Escherichia coli KNabc lacking three major Na+/H+ antiporters, and two genes psmrAB predicted to encode paired small multidrug resistance (PSMR) family proteins, the homolog of YvdSR, were finally cloned. Only the simultaneous presence of psmrAB, but not the single gene alone, conferred the tolerance of E. coli KNabc to up to 0.6 M NaCl and at alkaline pH. pH-dependent Na+(Li+)/H+ antiport activity was detected from everted membrane vesicles prepared from E. coli KNabc cells carrying psmrAB, which had the highest activity at pH 9.0. However, a detailed test for antimicrobial drugs showed that E. coli DH5a with psmrAB only exhibited slight resistance to chloramphenicol, but not other representative antimicrobial drugs especially ethidium bromide. Protein sequence alignment showed that neither PsmrA nor PsmrB has homology with known single-gene or multiple-gene Na+/H+ antiporters, or such proteins as TetA(L) and MdfA with Na+/H+ antiport activity. Taken together, PsmrAB should function mainly as a novel two-component Na+/H+ antiporter. This is the first example of a PSMR family member that exhibits Na+/H+ antiporter activity.